Classification of check valves and detailed explanation of their working principles

In fluid control systems, check valves are an important type of valve, and their main function is to prevent fluid from flowing back in the pipeline and ensure the stable operation of the system. According to different structures and working principles, check valves are subdivided into many types, among which the most common ones include swing check valves and lift check valves. Although these different types of check valves have certain differences in opening and closing actions, they all follow the same opening and closing principle, that is, using changes in fluid pressure to drive the opening and closing of the valve disc.

The swing check valve is a sophisticated valve with a valve disc tightly connected to the valve body through a hinge mechanism, which allows the valve disc to rotate freely around the hinge. When the fluid flows forward in the pipeline, the fluid pressure gradually increases and acts on the valve disc, pushing the valve disc to rotate around the hinge mechanism, thereby opening the valve and allowing the fluid to pass smoothly. In this process, the rotation angle of the valve disc is usually large to ensure that the fluid can fully enter the valve and reduce flow resistance. When the fluid tries to flow in the opposite direction, the valve disc will rotate around the hinge mechanism and close the valve under the combined action of the fluid pressure and its own gravity, effectively blocking the backflow of the fluid.

Unlike the swing check valve, the valve disc of the lift check valve moves up and down along the axis. The design of this valve is relatively simple, but it can also effectively achieve unidirectional flow control of the fluid. When the fluid flows in the forward direction, the fluid pressure gradually increases and acts on the bottom of the valve disc, pushing the valve disc up along the axis, thereby opening the valve channel. At this time, the fluid can pass through the valve smoothly and continue to flow along the pipeline. When the fluid stops flowing or tries to flow in the opposite direction, the fluid pressure decreases rapidly, and the valve disc descends along the axis under the action of the fluid pressure and its own gravity, gradually closing the valve channel. Once the valve disc is completely closed, it will effectively block the backflow of the fluid, ensuring that the fluid in the pipeline can only flow in the predetermined direction.

Although there are certain differences in the opening and closing actions of the swing check valve and the lift check valve, they all follow the same opening and closing principle, that is, using the change of fluid pressure to drive the opening and closing of the valve disc. This principle enables check valves to play an important role in various fluid control systems, preventing fluid backflow, reducing system pressure fluctuations, and protecting pumps and other fluid equipment from damage.

In addition, check valves also have the advantages of simple structure, easy installation, and low maintenance cost. This makes them widely used in various industrial fields, such as water supply and drainage systems, fire protection systems, petrochemicals, etc. In these fields, check valves can effectively ensure the stable operation of the system, improve production efficiency, and reduce maintenance costs.

As an important part of the fluid control system, the classification and working principle of the check valve are of great significance to ensure the stable operation of the system. By deeply understanding the working principles and characteristics of different types of check valves such as swing check valves and lift check valves, we can better select and use these valves to meet the needs of different fluid control systems.